This study investigated the relationship between the sleep-wake cycle and body mass index (BMI) of female shift-working nurses and examine the mediating effect of sleep quality on this relationship. We recruited a total of 147 female nurses working monthly rotating shifts at a teaching hospital in Taiwan from the day (n=63), evening (n=50), and night (n=34) shifts. Our research instruments utilized a questionnaire to collect demographic and work-related information, the Pittsburgh Sleep Quality Index (PSQI), and actigraphs to record sleep patterns for seven consecutive days. The sleep-wake cycles were then estimated using the dichotomy index (I<O). The I<O values were negatively associated with both BMI (β=-0.28, p=0.001) and PSQI scores (β=-0.29, p<0.001), the bootstrapping results indicated that the estimate of the indirect effect was -0.28, and the 95% confidence interval ranged from -0.68 to -0.05. For female shift-working nurses, sleep quality mediates the influence of the sleep-wake cycle on BMI, indicating that the maintenance of a regular sleep-wake cycle and good sleep quality could be important for female shift-working nurses.
Keywords: Body mass index; Female; Shift-working nurse; Sleep quality; Sleep-wake cycle.